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I set up the roller stand to hold the overhang weight, and allow table movement in one direction. Once set up the table moved normally. I don't think I ever got over 500 lbs. Had no crane to lift. Probably had a hand getting it on the table .

I know this a machining website, but I think the tub frame from an 1850, 1950 or 1900 would be the best solution. Hard to say from OP but sounds like you're getting a new tub anyway. They are quite a bit wider to allow perkins or Detroit engine to fit. I believe it would bolt on to your 1650 transmission. I have heard, but never seen, that a 5.9 cummins is a near drop in replacement for perkins on 1850. That is likely where the SAE bell housing for your conversion came from

Try a head grinder
If cost to high then hand scape like would for lathe
Both will work
For the holes just pilot type boring bar or if hole out of round use harden drill bushing and a ream

Dave

Originally Posted by Grunex125

Hi all:
Heres one for consideration, ideas sure are welcome.

In a few weeks or so I will be starting on a machining project that is sure to test the rated capacity of my Bridgeport mill. This is not a matter of do or don't it must be done plain and simple. I have on our farm a Oliver 1650 tractor that was repowered with a cummins B series diesel. when the shop originally did the repower they cut the cast iron frame with a plasma torch to make way for the oil pan and had to remove the engine mounts to make way for the bell housing. The problem being is that the heat that was generated from the Plasma torch ultimately set up a stress fracture in the frame and it was cracking and would soon break completly through if we had left it go. Don't get me wrong it's been twenty four years since we repowered, but still...........the crack has been there for a long time and gradually getting worse.

What I am dealing with is white cast that is 1.250" thick at it's thinnist point, the frame will weigh in excess of 500 lbs, is approx. 7.5 feet long, 14" deep, and 20" wide.

What I am thinking of doing is lay a couple of pieces of heavy channel iron across the table and secure channel to table and set the frame on top of that and secure into channel.
I can secure the frame to the table but will depend on using the ram to move from one side of the frame to the other to cut out both sides of the oil pan hole with only slight movement on the y axis. I don't need to be real precise, +,- .050 on all sides but I do need to hog out about .750" on both sides.
I'm planning on running low rpms with a roughing end mill, and having to reset every 20" of x travel. Because I know heat is what set up the crack originally, I'm thinking of retrofitting a windshield wiper pump and makeshift resivore for flooding with coolant. With the oil pan hole hopefully successfully machined I will have to flip the frame over to machine the engine mounts out.

Outside of the obvious, heavy, big item and awkward to handle what are some of the pitfalls I should look out for?

I've been machining for 25 years, but never tackeled anything this big and cast at that, so I'm open for suggestions.

thanks in advance, pls Google Oliver 1650 tractor to get an idea of what I am about to undertake.

To clarify, are you doing additional modifications to your existing frame that has a crack in it, or are you machining a different frame to fit your modified tractor? If you are starting with a new frame and doing the mods needed by machining rather than what was done with a torch, then i suggest you take the advice from Forrest Addy and rig up some secure counter weights. That, plus your idea for using channel to skid the frame into rough position should work fine.

Have you considered a weld repair on the existing frame? This might involve adding additional support to the frame, followed by stress relieving the finished job, but might be easier and stronger in the long run.

WTF!!! Is that IT?? That's a SawzAll and bi-metal blade job. Dress it up with an angle grinder. Take you about 8 hours about the same time as setting it up and cutting clearance on a Bridgeport. If you do a good job it will be neat and contoured as if cast in that shape.

Balance it out. 8 hours of moderately vigorous had metalwork and $50 of SawzAll blades Vs certain damage to a $3000 Bridgeport.

A little economical smart sweat VS lazy heedlessness. This is one of those situations where there is no replacement for honest work.